One area of recent advancement is the development of different memory types, each with different characteristics. An important aspect of a majority of electronic devices is the ability to store information in digital memory, which stores information as a series of I/Os. Digital memory is a broad category with many different types of subset memory. In particular, flash memory is a type of electronic memory media that can be rewritten and that can retain content without consumption of power. Unlike dynamic random access memory (DRAM) devices and static random memory (SRAM) devices in which a single byte can be erased, flash memory devices are typically erased in fixed multi-bit blocks or sectors. Flash memory technology can include NOR flash memory and NAND flash memory, for example. NOR flash memory evolved from electrically erasable read only memory (EEPROM) chip technology, in which, unlike flash memory, a single byte can be erased; and NAND flash memory evolved from DRAM technology. Flash memory devices typically are less expensive and denser as compared to many other memory devices, meaning that flash memory devices can store more data per unit area.
In addition to being readable, re-writable (e.g., erased and written to again), and non-volatile, flash memory is relatively cheap to mass-produce. The economic factor makes flash memory much more appropriate for personal applications, such as storing of digital photographs and storing digital music files. Flash memory devices generally have a life span of about one million programming cycles. Flash memory can be used in many portable electronic products, such as cell phones, portable computers, voice recorders, thumbnail drives and the like, as well as in many larger electronic systems, such as cars, planes, industrial control systems, etc.
In conventional flash memory, disturbances can occur during the programming and/or read and/or erase operation. Typically, these disturbances are due to electron injection during the operation and can cause errors in programming, reading or erasing. Furthermore, disturbances also can be experienced by memory cells neighboring a selected memory cell during an AC (alternating current) operation, such as, programming, reading and/or erasing. This can cause current to flow through a neighboring cell, which could reprogram the neighboring cell and result in incorrect data.